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In a new study published in the journal Nature, the researchers found that baleen whales actually consume nearly three times more krill than originally thought.
The study observed seven tagged baleen whales that traveled across regions from the Atlantic and Pacific to the Southern Oceans. Using drones, echo sounders and tags, the researchers were able to measure the density of krill in the baleen whale region, as well as the daily and annual consumption of baleen whale prey.
The researchers were able to determine that previous studies grossly underestimated the consumption of baleen whales. Whales actually eat a lot more.
Before the commercialization of whaling, baleen whales consumed 430 million tonnes of Antarctic krill per year. This is double the current population of Antarctic krill today and more than double the annual global catch from the marine fishery.
Baleen whales play a large role in global ecosystems, especially in their feces. Essentially, they act as krill processing plants and disperse the nutrients contained within the krill back into the ocean ecosystem. The realization that baleen whales are actually consuming much more than originally thought echoes the cries of conservationists about why we need to save the whales.
What are Antarctic krill?
Antarctic krill are the most populous animal species on Earth. Their total biomass ranges from 125 to 750 million metric tons. These creatures are small and look like the more famous crayfish.
Antarctic krill extend from the Antarctic continent to the polar front. They swim in dense flocks and are hunted by many other species. Most large species of whales, leopard seals, some penguins, albatrosses, other fish and even squid prey on this species of krill.
In fact, Antarctic krill are the staple food of marine life.
Even after being digested, Antarctic krill continue to feed the ocean. Inside the krill are nutrients such as iron that help nourish phytoplankton, which is the backbone of the ocean’s ecological food web. Phytoplankton are krill food and need iron to survive.
Antarctic krill are one of the key intermediaries in the marine food chain. Without them or consuming them, everything else will eventually die out.
Why are baleen whale diets important?
This study extrapolates data from researchers to determine consumption rates for baleen whales prior to commercial whaling.
Industrial whaling has killed 80% of the whales in the Southern Ocean in just 60 years. This has led to a 90% reduction in the baleen whale population. This shows that with larger populations of whales, marine ecosystems are much more productive.
The marine ecosystem is a cycle in which whales, krill and phytoplankton are key players: Antarctic krill feeds whales; whales absorb nutrients needed for phytoplankton; phytoplankton feeds krill; ultimately, other marine species rely on these three functions to survive.
Showing the importance of baleen whales to productive marine ecosystems, this study further highlights the importance of restoring whale populations. If we support the whales of our world, we will ultimately benefit the health and functionality of the entire ecosystem.
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